Book/Report

FZJ-2020-01460

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Organisch-geochemischer Vergleich ausgewählter Gesteine der Frasnium/Famennium Grenze (Oberdevon) im Bergischen Land und der Eifel

Kloppisch, M. (Corresponding author)FZJ*

2002
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/24538

Report No.: Juel-3987

Abstract: The present work deals with the organic-geochemical characterization of the socalledPhytoplankton-Blackout" at the Frasnium-Famennium boundary (F-F). Forthis purpose, samples of preferentially low thermal maturity from sequences ofalternating shales and limestones were taken from boreholes brought down in theRheinische Schiefergebirge (Rhenish Slate Mountains).Preliminary investigations were carried out from the well Knoppenbissen, witchproved to be unsuitable for further studies an molecular composition of organicmatter due intense tectonic overprint in this area. For detailed analyses, 31 samplesfrom the well Büdesheimer Bach and 53 samples from the well Paffrather Muldewere available.In general, all samples derived from the two latest mentioned localities can beassigned to as immature. Temperatures measured at times of maximal pyrolyseyield Show little variation (425 ...43°C) and correspond to a vitrinite reflectance ofapproximately 0.5%R$_{\tau}$.Comparison between the sections Büdesheimer Bach and Paffrather Mulde exhibitsslight differences in the molecular composition of organic substances. Basedan the distribution pattern of n-alkanes documented in the chromatograms, thematerial from the well Büdesheimer Bach proved to be less mature as compared tothe well Paffrather Mulde.The total organic carbon content ranges from 0.12% in relatively pure carbonatesto exceptionally high values of up to 7,53% in one of the Kellwasser-horizons.The higher amounts of organic carbon recorded in the Kellwasser-horizons points toa consolidated deposition of organic material in the course of the "Phytoplankton-Blackout"-Event.Analyses an the molecular composition of organic matter were carried out an15 samples from well Büdesheimer Bach and Paffrather Mulde, each. The predominanceof C$_{15}$ to C$_{17}$ in the distribution pattern of n-alkanes gives evidence thatalgae and bacteria contribute to a significant portion of organic matter in the rocks investigated. It was not possible, through, to trace a mass extinction of phytoplankton.Evidences for an extinction was mirrored by high total organic carbon contents.Another hint results from reducing conditions at times of deposition, that could bedetected by means of the pristene/phytene-ratio (Pr/Ph) as well as by the amountof hydrocabons released during pyrolytic degradation of organic matter (Hydrogen-Index, HI).

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000 ; Retrocat)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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Database coverage:

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